Case IH 13250 - UCM – Universal Control Module (UCM): ISOBUS bus-off with the engine running

Frequently a false diagnostic caused by bad software logic when the operator performs a "fast key cycle" (turning the ignition key too quickly during startup).

• VESTRUM CVX
• Puma CVT
• Maxxum CVT
• Optum CVT

1. 1

   Operator Interview: Ask the operator if the code appeared immediately after a rapid ignition key cycle.

2. 2

   Software Verification: Connect the CNH Electronic Service Tool (EST) and check the current software version of the Universal Control Module (UCM).

3. 3

   Bus Check: Verify if there are actual physical ISOBUS communication issues with implements, or if the code is purely a phantom/false code with no operational symptoms.

1. 1

   Connect a laptop with the CNH Electronic Service Tool (EST) to the tractor's primary diagnostic port.

   Connect a laptop with the CNH Electronic Service Tool (EST) to the tractor's primary diagnostic port.

2. 2

   Open the EST software and press the "Detect Vehicle" button.

   Open the EST software and press the "Detect Vehicle" button.

3. 3

   Navigate to the Universal Control Module (UCM).

   Navigate to the Universal Control Module (UCM).

4. 4

   Flash/update the UCM software to the latest version (2022 or newer, as per KA000006045).

   The updated software contains the patch that corrects the faulty logic and prevents the false 13250 diagnostic.

5. 5

   Clear all inactive fault codes.

   Clear all inactive fault codes.

6. 6

   Perform a normal key cycle, start the engine, and verify that the ISOBUS bus-off code does not return.

   Perform a normal key cycle, start the engine, and verify that the ISOBUS bus-off code does not return.